1. Field of the Invention
The present invention relates to an image pickup unit which is contained in an insertion portion distal end portion of an endoscope including an insertion portion which can be introduced into a subject.
2. Description of the Related Art
In recent years, endoscopes have been used in various medical fields such as internal medicine, surgery or the like. In a surgical operation, in order to decrease invasion to a patient, a laparoscopic surgical operation of performing curative treatment without performing abdominal section is performed. In a laparoscopic surgical operation, a trocar which guides an endoscope for observation into a body cavity, and a trocar which guides a treatment instrument to a site to be treated in the body cavity are punctured into an abdomen of a patient. As the endoscope for observation, a so-called rigid endoscope (hereinafter, also simply described as a rigid scope) is used, in which a bending portion is not present in the vicinity of a distal end of an insertion portion and the insertion portion is formed of a rigid member.
Further, in recent years, for example, a rigid scope with a bending portion which includes the bending portion in the vicinity of a distal end portion has been used as a rigid scope.
Meanwhile, an endoscope (hereinafter, also described as a flexible endoscope) is used, which enables observation by insertion of an insertion portion elongated and having flexibility into a body from natural openings such as a mouth and an anus, or various remedies or treatments by insertion of a treatment instrument into a treatment instrument channel provided in an insertion portion in accordance with necessity. Generally in a flexible endoscope, a bending portion is included in the vicinity of a distal end portion, and the above described bending portion can be bent in response to an operation of a user.
Rigid endoscopes and flexible endoscopes include optical endoscopes and electronic endoscopes. In an optical endoscope, an optical image observed through an observation window is transmitted to an eyepiece portion by an image guide configured by an optical fiber bundle inserted into an insertion portion or a relay lens, and, for example, a surgeon can visually perform observation by peeping into the eyepiece portion.
Meanwhile, in an electronic endoscope, an optical image observed through an observation window is formed on an image pickup surface of an image pickup device such as a CCD which is placed at a distal end portion of an insertion portion. The optical image which is formed on the image pickup surface is converted into an electric signal in the image pickup device, and thereafter, is transmitted to a video processor and is converted into a video signal. Subsequently, the video signal is outputted to a display apparatus, whereby an endoscopic image is displayed on a screen and can be observed. In the electronic endoscope, reduction in diameter of the insertion portion and observation by a high-quality image are enabled by miniaturization of the image pickup device and increase in the number of pixels.
An electronic endoscope contains an image pickup unit including an expensive compact electronic component such as an image pickup device in the insertion portion. Accordingly, an electronic endoscope is generally expensive as compared with an optical endoscope in which an image guide or a relay lens is inserted through an insertion portion.
In an electronic endoscope, an endoscopic image is displayed on a screen of a display apparatus, and therefore, the advantage is provided, that observation by a plurality of users can be easily performed. In an optical endoscope, an endoscopic image can be displayed on a screen of a display apparatus by an image pickup camera (also called a camera head) including an image pickup device being fitted on an eyepiece portion.
In an electronic endoscope, the endoscope is connected to a video processor, and thereby, an optimal endoscopic image for observation is displayed on the screen of the display apparatus. In the electronic endoscope, a use state of the endoscope connected to a video processor is temporarily registered in the video processor, and thereby, an optimal endoscopic image can be obtained and observed repeatedly when the aforesaid endoscope is connected to the video processor again. Like this, an electronic endoscope has the advantage of being capable of easily displaying an endoscopic image on the display apparatus by the endoscope being connected to a video processor.
In contrast with this, in the configuration in which an image pickup camera is fitted to an eyepiece portion of an optical endoscope and an endoscopic image is displayed on the screen, the image pickup camera is attached to the eyepiece portion, and thereafter, focus has to be achieved so that the endoscopic image forms an image in a predetermined state on an image pickup surface of the image pickup camera. In other words, it may be difficult to obtain an endoscopic image optimal for observation only by attaching an image pickup camera to the eyepiece portion and connecting the image pickup camera to a video processor.
However, in the field of a rigid scope, an optical endoscope is less expensive as compared with an electronic endoscope. Accordingly, a larger number of optical rigid scopes are used as compared with electronic rigid scopes.
In the case of a laparoscopic surgical operation, the operation is generally performed with a system having a plurality of surgeons and nurses and a plurality of surgeons observe an endoscopic image displayed on a display apparatus and perform the operation. However, in an optical endoscope, in order to display an endoscopic image on the display apparatus, an image pickup camera needs to be fitted on the eyepiece portion of the endoscope as described above, while an operation of achieving focus or the like is required, and it may be sometimes difficult to obtain an optimal endoscopic image for observation easily.
Accordingly, in the field of a rigid scope for use in a laparoscopic surgical operation or the like, an electronic rigid scope capable of easily displaying a high-quality image on the screen of a display apparatus is also desired.
However, an electronic endoscope has the advantage of being capable of easily displaying a high-quality image on the display apparatus on one hand, but on the other hand, it has the disadvantage of being expensive as compared with an optical endoscope which is simple in configuration and low in component cost and assembly cost. Especially in a flexible endoscope, miniaturization of the image pickup unit is pursued for the purpose of insertability, reduction in pain of patients, and the like, and therefore, the components in use are microscopic, and much time is required in assembly, which results in a high price.
Accordingly, in an electronic endoscope, various improvements concerning reduction in cost of an image pickup apparatus have been proposed. For example, Japanese Patent Application Laid-Open Publication No. 10-216084 (hereinafter, described as Patent Document 1) shows an image pickup apparatus for an endoscope in which the image pickup apparatus at low cost can be obtained. In the image pickup apparatus for an endoscope, terminal surfaces are provided in a step shape at one circuit board, and a connecting terminal for duodenum is formed on one terminal surface in the step shape, whereas a connecting terminal for stomach is formed on the other terminal surface.
In Patent Document 1, a lead attached to a CCD is selectively connected to the connecting terminal for duodenum or stomach formed on the circuit board, whereby the attaching position of the CCD is changed, and the image pickup apparatus for duodenum and the image pickup apparatus for stomach can be obtained with one circuit board.
Further, it is conceivable to configure an image pickup unit, for example, with use of a board on which an electronic component is mounted and an image pickup device and a signal line such as a coaxial cable are connected as a common component, in a rigid scope and a flexible endoscope (or a rigid scope including a bending portion). In this case, commonality of the component can be achieved between endoscopes of different types with and without a bending portion, and therefore, the advantage of being capable of contributing to reduction in the number of process steps of management of components or the like, or cost reduction is provided, in terms of commonality between the aforesaid endoscopes of different types.
Generally in the case of an endoscope including a bending portion such as a flexible endoscope, for example, there is a demand for making the length of the rigid portion as short as possible from the viewpoint of reduction in pain at the time of insertion into the body of a patient, or enhancement in operability of the distal end portion at the time of bending. In an electronic endoscope, the size, mainly the total length of the image pickup unit which is housed in the rigid portion, exerts an influence on the length of the rigid portion.
In order to respond to the demand for making the total length of the rigid portion as short as possible, in many image pickup units for use in the endoscopes including the bending portions, connection regions for connecting the signal lines provided on the boards are usually configured to be an extremely limited spaces so that the total lengths thereof can be made short.
Since the connection regions are limited spaces, when the signal lines are connected to the boards, mechanical connection is difficult, and therefore, connection is left to manual work. More specifically, precision work is required of a worker, and the number of working process steps at the time of assembly tends to increase.
Meanwhile, for example, in the case of electronic rigid scopes without having bending portions, the demand concerning reduction in the length of the rigid portions is not high as compared with the endoscopes including bending portions. However, electronic rigid scopes tend to be expensive as compared with optical rigid scopes, and therefore, less expensive electronic rigid scopes are desired.
As described above, different demands are present between rigid scopes, and rigid scopes with bending portions including bending portions and flexible endoscopes.